Update table from one database with data from another database

Hello I have 2 MySQL databases on the same server with same structure and same data. Occasionally data in one database are changed for 7 days and then should be back to the same value as in first database. Through PhpMyAdmin I am trying to write statement that should do thi but something I am missing. I have databases: db1_local and db2_local Table gitem column gbaseprice (should be synchronized from db1 to db2) column gitemcode (has same value in both databases and synchronizing should be followed with this parameter so that id's don't mess up) Appreciate any help